High pressure sensors are utilized in a wide range of sensing applications. For such applications, differential pressure sensors may accurately sense the pressure of a fluid media. Such differential pressure sensors can be configured utilizing semiconductor technology. The most common differential pressure sensors are solid-state silicon pressure sensors. The pressure sensors may incorporate a pressure sense die to measure the media pressure by detecting the difference in pressure between two pressure ports of the high pressure sensors.
Additionally, the pressure sensor die of the pressure sensor can be squeezed between two elastomer seals by an external package. One of the elastomer seals is electrically conductive in order to connect a number of electrical terminals or molded leads to the pressure sense die. The sensitive pressure sense die can be sandwiched between the elastomer seals contained within a plastic housing. Such a pressure sensor design allows the conductive seal to be slightly offset relative to the pressure sense die in the plastic housing due to manufacturing tolerances. The conductive elastomeric seal can be compressed against the sense die in order to make a pneumatic seal and good electrical connection.
Moreover, the conductive seal includes silver filled regions, which establish electrical contact with pads on the face of the sensor die. The conductive path can extend from the die pads through the seal in a z-axis to the leads molded into the mating surface of the sensor package on the other side of the conductive seal. The conductive seal may, however, cause an electrical short if the die pads are forced over the edge of the sense die, because the sense die typically constitutes a semiconductor. In particular, electrical shorting occurs when the conductive seals wrap over the edge of the sense die. The electrical shorting may short out a Wheatstone bridge or other electronic circuitry located on the sensor package such that it changes the sensor output intermittently. This intermittent sense output is difficult to detect during manufacturing and results in a “die-edge shorting” in the pressure sensors.
A prior pressure sensor utilizes a spring slid into a circular sleeve punched out of an elastomer seal. Such a conductive seal can also exhibit an inherent electrical shorting problem with the sense die if perfect alignment is not held when the package is snapped together. Therefore, a die-edge shorting may occur when the sense die is compressed against the seals, which can lead to a sensor malfunction or failure. Hence, it is more desirable to prevent the sensing die, circuitry and electrical connections from exposure to die-edge shorting in order to ensure reliable operation of the pressure sensor.
Based on the foregoing it is believed that a need exists for an improved conductive seal, which prevents die-edge shorting with the sense die and which is ultimately more efficient and sturdier than presently implemented pressure sensors. Such conductive seals are described in greater detail herein.